The present disclosure relates to an electric storage apparatus, and an electronic device, an electric vehicle, and an electric power system taking advantage of electric power from the electric storage apparatus.
In recent years, uses for secondary batteries such as lithium-ion batteries and so forth have rapidly been expanded in electric power storage apparatuses for electric power storage, automotive batteries, and so forth combined with a new energy system such as solar batteries, wind-power generation, or the like. In the case of employing a great number of electric storage elements, e.g., unit batteries (also referred to as single batteries or cells. In the following description, referred to as battery cells as appropriate) to generate large output, a configuration is employed wherein multiple electric storage modules are serially connected. With the electric storage modules, a battery block is configured by multiple, e.g., four battery cells being connected in series and/or parallel. An electric storage module (also referred to as assembled battery) is configured by a great number of battery blocks being housed in an exterior case.
Further, there is a battery system according to the related art wherein multiple electric storage modules are connected, and a common control device is provided to the multiple electric storage modules. The electric storage modules include a module controller, and configured to communicate between the module controller and a control device via a communication tool.
In the case of using multiple battery cells, there may be a case where even if one of multiple battery cells has reached use lower limit voltage at the time of discharge due to difference in self-discharge of battery cells, or the like, other battery cells have not reached use lower limit voltage yet. Charging the battery cells again in such a state causes a problem in that a battery cell which is not sufficiently charged occurs, and the capability of the battery cell fails to be sufficiently be exhibited.
In order to correct such irregularities between multiple battery cells, balance between the battery cells has heretofore been controlled. Further, with Japanese Unexamined Patent Application Publication No. 2008-035680, description has been made wherein a great number of battery cells are divided into multiple series cell groups, an inter-cell voltage balance correction circuit is provided to the cell groups, and also an inter-group voltage balance correction circuit is provided thereto. The inter-group voltage balance correction circuits are configured to subject the series voltages of the cell groups to balance correction using AC coupling to be formed with a transformer coil and a switching circuit.